A Better Way to Measure Your Impact on the World

Close your eyes and think of an electric wheelchair. What do you see? Is it sleek, futuristic, and elegant… worthy of the moniker: iChair? No, no it is not. It’s a boxy tank-like thing with grey knobbed wheels that is powered with lead-acid batteries. Why is that?

Obviously there are alternatives. Just yesterday I came across UPnRIDE (that name is sore on the eyes but speak it aloud and you’ll get it). It’s an electric wheelchair that converts into a standing position. And it looks comparatively sleek and modern. And it’s not the first time I’ve seen the idea before. One of my favorite articles over the years is still our coverage of Tek RMD, a similar standing robotic wheelchair design. So why is it I don’t see these in the wild? Why is it I only remember seeing the concept twice in four years?

There are so many reasons — people don’t buy flagship wheelchairs like they do phones, and the money used to purchase them isn’t disposable income but money locked up in the healthcare-industrial-complex. This is a can of worms. For instance, that analogy breaks down when you consider that it’s okay for people to have crappy cellphones but not okay for them to have crappy wheelchairs. To traverse this particular detail let’s just say that once a piece of medical technology has been approved by mega-healthcare-entities there becomes a disincentive for manufacturers to go through R&D and start the whole approval process again.

I think one of the major problems we have as hackers, designers, and engineers is harboring a narrow scope of what we should call success. Is it getting a product to market, getting 1M hits on your demo video, or winning the Hackaday Prize? Sure. But small success matters. Really, the best things in life are very hard to measure — I want to leave you with an altruistic view.

Maybe we don’t have twelve different companies hitting the market with new and innovative robotic wheelchairs, (each with a different take), because we didn’t see enough of it ten years ago. Ten years ago there was a hacker, a junior in high school, learning about mechanical and electrical engineering and preparing to go on to college. Now that person has been out of school and on the job for four years. With a little experience under their belt (or perhaps a Masters of Engineering in their back pocket) they are looking for a good idea to start a company.

Maybe we missed the boat with that person. If we had really impressed them with an interesting idea, they may have carried it though, chipping away at the problem with student projects, and would now be ready to burst onto the scene with a really great idea. So we need more ideas. We need more proofs-of-concept, and more failed prototypes (and successful ones too). We need many iterations on the same problems. We need to show our work and thereby inspire others.

Yeah. My brother is in a wheelchair and that thing is a dinosaur. It weighs half a ton and is big as a forklift. Powered by lead-acid batteries… I’d like to see a lightweight chair built with those bicycle hub motors, and with modern batteries and electronics.

The same goes for all his assistive devices. They could really use some development. But, I guess there’s no money in this business…

It seems to me it should really be someone that has to use such a vehicle designing it. If you don’t fully understand the space that this has to function it, it would be very difficult to anticipate the various issues that need to be addressed. Just talking with a user may not be enough, because they may not realize what can and cannot be done and therefore cannot give a sense of what compromises are acceptable, and what are not. I suspect that it is a lack of broad usability across conditions because of this lack that is the reason these ‘standing wheelchairs’ are not that popular.

The rider needs to be able to stand close to a counter (bank teller, ticket agent, fast food cashier, etc.) to be truly effective, while able to open, close, and fit through doors. Also consider preventing pressure ulcers at the contact points.

Size is a problem with many scooters. I once helped a friend transport a mobility scooter to the second floor of a hotel. The scooter was almost exactly as long as the elevator was deep, so I had to drive it into the elevator at a speed fast enough to get to the door before it decided to close again, but slowly enough that I could stop without hitting the back of the elevator too hard. I failed at that second part, but no damage was done to either the scooter or elevator. :)
Then, I had to try to press the elevator button that was behind me (something that would have been very difficult for many people with mobility impairment) and then stare at the back wall of the elevator until I reached the desired floor.
A scooter with a smaller footprint and the ability to turn on its own center line would have been a big improvement.

When I used to repair electric wheelchairs I noticed all the houses with one had chipped door frames from the protruding axel bolts ( design FAIL) I happened one day to have a chair at home and gave it a run through my house in and out of each of the rooms. I then too had chipped door frames :o

One issue that needs to be addressed in the design of an improved wheelchair is suitability for air travel. Sealed lead acid batteries are approved for air transport while lithium ion batteries face ever increasing restrictions. Any wheelchair that uses lithium ion batteries should address this issue. A standardized battery (possibly one of the high power garden tool batteries for economy of scale) would make it easier to obtain a battery (either for purchase or rental) at the destination.

Or have a ni-cad option, trading shorter life for safety in the same size package. A shorter wheelbase and tank style steering are obvious, but will probably involve active balancing, especially if the passenger is vertical. All terrain/stair climbing would be a nice feature, but tough to accomplish in a general use vehicle. The hardest thing to get around is going to be the problem of fitting each user for a harness/framework which has to support a person in two different positions. Most chairs today are highly customized to provide support without creating pressure sores, doing this in a repositionable manner is going to require some fancy footwork.

One thing I forgot to mention in the article: the barrier for adding lithium-ion batteries to a wheelchair isn’t that of apathy. The failure of “tender” circuits in Li-ion cells means fire. This is a completely unacceptable risk when the user of the wheelchair might not be able to get out of it by themselves in the event of an emergency.

I hadn’t considered the air-travel issue. Is it common to check powered chairs gateside?

I don’t think it’s too common right now (but not unheard of), but when new wheelchair designs allow the users more freedom, people will want to travel.
It’s similar to the early days of handicapped parking spaces, ramps, etc. They didn’t see much use because few handicapped people would venture out into public spaces because of the difficulty. Slowly, people realized that more and more public spaces were accessible and ventured out.

I saw a demo at a FIRST Robotics competition around 2006 or so. Jim Langevin, a U.S. Representative from Rhode Island and a quadriplegic, demonstrated it by driving out onto the floor on four wheels, giving a brief introduction, and then saying, “watch this!” while he flipped the switch to go up onto two wheels, to be at “eye level” with others. It gained a standing ovation, and was a terrific demo.

I checked taobao a few weeks ago and found that the cost had really dropped for LiFePO4. There were pouch and canister cells that were tempting, some clearly designed for large vehicles. It might be a case of ‘you get what you pay for’ or it might be a good deal… When I’ve got some spare cash I plan to buy a few and share the test results.

having had to work on my mom’s scooter (both of them, shes on her second one), its like going back in time many many years. the hardware is pretty straightforward, a motor controller, a couple lead acid batteries and a pretty basic control panel. her first scooter had a nice computerized panel and weather resistant controls, the new one just has a bunch of panel mount gear soldered directly to a wiring harness. ive had to replace many switches and buttons on that thing since nothing is weatherproofed (and its very rainy here).

a couple things get me about the way they are put together. first they use a magnetic break, and the coil is on in the released position so the thing is wasting power the whole time you use the scooter. i assume this is a safety feature so that the scooter becomes stationary when the throttle is released. but why not instead use hbridge breaking instead? the motors are all brushed dc as well, and not the good ones with the neodymium magnets, is that the best they could come up with?

the other thing i notice is that the motor controller, which even in scooters with computerized controls, is the brains of the operation. there is software to tweak the settings, like torque curves and the like. but it is locked down, you need a usb dongle to unlock the software. the only way to get the dongle is to complete their overpriced certification course (which i assume is due to health care bureaucrats), and only then will they sell you one at an absurd price point, and the serial cables are also at an absurd price point, even though its likely just a usb ttl bridge with a proprietary connector. id love to see a mobility scooter hacking board pop up out there to help knock down some of these artificial borders.

fortunately what can be hacked is the battery system, the controller doesnt really care where its voltage comes from so long as it sees 24v its happy. the charger is just a basic 24v charger brick, and it looks like a dumb charger at that, its not doing anything to keep the batteries in good shape. i have a shed full of dead scooter batteries to attest to that. i have found battery mods out there. one ive been interested in is to shove a thousand bucks worth of lifepo4 cells and a smart charger in the space where the lead acid batteries would go. that would certainly help the battery life and really cut down the scooter’s dry weight.

How much power is the brake wasting? Seems like a reasonable precaution in case the battery gets suddenly completely disconnected. And probably the energy waste is only a percent or two of what the motor uses.